According to the Facebook executive, effective immediately the company is extending its paid bereavement leave to up to 20 days to grieve the death of an immediate family member and up to 10 days to grieve the death of an extended family member. Facebook is also expanding its paid family leave to up to six weeks for employees to care for a sick relative. Finally, the company is also introducing paid family sick time, which offers employees three days to take care of a family member with a short-term illness like the flu.

The news comes at a critical time for American families: Under the Family and Medical Leave Act of 1993, qualifying American are guaranteed 12 weeks of "reasonable" leave for certain family and medical situations including caring for a family member with a serious health condition.

While the law requires companies with 50 or more employees to provide new parents with 12 weeks of leave, it doesn't require this leave to be paid, and the policy is also restricted to full-time employees who have been with the company for more than a year, which, all told, applies to about 60% of workers in the US.

Though the number of companies expanding their paid parental leave benefits is rising, Sandberg acknowledged that it's less common for employees to get paid time off to care for sick loved ones, saying that the US needs public policies "that make it easier for people to care for their children and aging parents and for families to mourn and heal after loss."

"People should be able both to work and be there for their families," Sandberg wrote. "No one should face this trade-off."

Considering the US's lack of federal paid family leave policy, Sandberg said companies need to take the lead and support families with their own paid leave policies, which she said wouldn't just be nice to do, but would also improve the bottom line by increasing employee loyalty and performance.

"I hope more companies will join us and others making similar moves, because America's families deserve support," Sandberg wrote.